package com.yw.utils;

import org.apache.commons.lang3.Validate;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/**
 * ApplicationContext的帮助类 自动装载ApplicationContext.
 * 
 * @author devintam
 * 
 * @date 2015-06-30
 * 
 */
public class SpringContext implements ApplicationContextAware, DisposableBean {

	private static ApplicationContext applicationContext = null;

	public static Log logger = LogFactory.getLog(SpringContext.class);

	/**
	 * 取得存储在静态变量中的ApplicationContext.
	 */
	public static ApplicationContext getApplicationContext() {
		assertContextInjected();
		return applicationContext;
	}

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	@SuppressWarnings("unchecked")
	public static <T> T getBean(String name) {
		assertContextInjected();
		return (T) applicationContext.getBean(name);
	}

	/**
	 * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
	 */
	public static <T> T getBean(Class<T> requiredType) {
		assertContextInjected();
		return applicationContext.getBean(requiredType);
	}

	/**
	 * 清除SpringContext中的ApplicationContext为Null.
	 */
	public static void clearHolder() {
		logger.debug("清除SpringContext中的ApplicationContext:"
				+ applicationContext);
		applicationContext = null;
	}

	/**
	 * 实现ApplicationContextAware接口, 注入Context到静态变量中.
	 */
	public void setApplicationContext(ApplicationContext applicationContext) {
		// logger.debug("注入ApplicationContext到SpringContext:{}",
		// applicationContext);

		if (SpringContext.applicationContext != null) {
			logger.warn("SpringContext中的ApplicationContext被覆盖, 原有ApplicationContext为:"
					+ SpringContext.applicationContext);
		}

		SpringContext.applicationContext = applicationContext; // NOSONAR
	}

	/**
	 * 实现DisposableBean接口, 在Context关闭时清理静态变量.
	 */
	public void destroy() throws Exception {
		SpringContext.clearHolder();
	}

	/**
	 * 检查ApplicationContext不为空.
	 */
	private static void assertContextInjected() {
		Validate.validState(applicationContext != null,
				"applicaitonContext属性未注入, 请在applicationContext.xml中定义SpringContext.");
	}
}